对汶川8·0级地震前后震源的重新定位

龙门山断裂带二侧的地壳厚度和速度结构存在很大差异,所以过去采用的单一均匀速度模型定位方法并不合适。Hypo2000定位程序对震中所在的不同区域进行分区分层对应,得出非均匀速度模型。用Hypo2000定位程序对汶川8·0级地震前后十余年187个地震台网记录进行了整理、筛选,得出震中分布图显示震前龙门山断裂带北端,即北川以北没有太多地震,主要还是活跃在中南部映秀地带,汶川8·0级地震也发生在这个地区,震后沿龙门山断裂带往北,北川以北出现了较多的余震。从余震深度剖面图看出,龙门山余震带南段断裂带呈上陡下缓的铲形断裂形态,余震带北段具有近乎直立的陡倾破裂结构,且地表破裂的二侧均有余震分布。

RELOCATION OF THE EPICENTRE BEFORE AND AFTER WENCHUAN MS 8.0 EARTHQUAKE

The crustal thickness and velocity structure in both sides of Longmenshan fault zone are very different,so in the past using a single uniform velocity model was not appropriate positioning method,Hypo2000 locator epicenter located in different regions of the partition layer corresponds to come to non-uniform velocity model.In this paper,Hypo2000 locator for 187 seismic Network records before and after Wenchuan 8.0 earthquake 10 years are sorted and filtered.Draw the epicenter distribution shows the earthquake was not too much in the north of Longmenshan fault zone including the north of Beichuan before earthquakes,mainly still active in Yingxiu south area,and 8.0 magnitude earthquake happened in this region.After the earthquake Longmen mountains to the north along the fault zone to the north of Beichuan appeared more aftershocks.From the depth profile of aftershocks Longmen mountains,it shows that southern aftershocks belts has the characteristics of fault zone steep slowly shovel form fracture form,but in the north of the aftershocks belt,it has almost vertical steep loose broken structure,and the surface of the broken in both sides are corresponded to the aftershocks distribution.